Applications of fittings and fitting assemblies for air tube and hose line connections in industrial and commercial environments require resistance to harsh environmental conditions and reliability under stress during installation and operation. For example, in applications in the freight hauling trucking and transportation industry, tractor-trailer air brake fittings and hose and tube assemblies undergo continuous exposure to the elements, often in frigid conditions. Winter road salts and brine, dirt, grease, and other solvents erode fittings and assemblies of critical air brake tube and hose connections, putting the safety of the driver and highway motorists at risk.
Tube and hose lines, as well as grips, fittings and connectors/couplings for such tube and hose lines used within harsh industrial and commercial environments generally must withstand such harsh environments as well as perform reliably under the stress and strain forces encountered during installation and operation. Such tube and hose lines may involve high pressure hydraulics or air and often require some flexibility of the tube or hose. It should be understood that the terms “hose” and “tube”, while often used interchangeably, are technically different components. Hoses are generally reinforced in some way, normally with imbedded braid reinforcement, wire reinforcement, reinforcement with a stiff plastic, dual walls, or a single heavy wall. Hoses are often used and rated for applications that involve high pressure. Tubing, on the other hand, is not reinforced, or is sparsely reinforced, and is often used for gravity flow or lower pressure applications.
Hoses and tubes are commonly used in applications within the freight hauling industry, for example, to supply pressurized air for air brake operation between a tractor cab unit and a freight trailer, or from a locomotive to railway air brakes on railroad cars. Inherent to the freight industry is the constant coupling and decoupling of hoses/tubes as trailers are left for loading or unloading and other trailers are picked up for delivery. Various types of components such as gladhand connectors (couplers resembling a pair of “hands shaking”), grips and couplers/connectors, including swivel couplings, are used to interconnect hose/tube sections to other hoses/tubes sections and to terminals.
During installation and operation of such hoses and components in the freight hauling context, stresses from bending, twisting, and kinking are experienced. For instance, tractor-trailer operators subject air brake lines to twisting while bending them into position in tight quarters between the tractor and trailer. Drivers and fleet maintenance personnel repetitively connect and disconnect air brake lines between the tractor and trailer using hand holds on the hose at the fittings to achieve the needed leverage to secure and release gladhand connections. Connection of tractor to trailer using integrated, multiple hose and tube assemblies, or “kits”, often wrapped or covered with abrasion resistant materials, requires flexibility in the manner of coupling the multiple fittings to their respective fixed air and hydraulic connections.
Conventional grips and couplers/connectors including swivel couplings, however, do not offer sufficient protection against kinking of the hose and tube, particularly at the gladhand connections and occasionally in tractor connections where the ports are mounted higher and their output is pointed vertically requiring the hose to bend toward the trailer, and are difficult to install and not sufficiently reliable during operation. Conventional hose and tube assemblies using only coiled springs or bend restrictors of a thin, flimsy or too-rigid materials and sometimes of a not-firmly attached nature at the fittings provide inadequate protection from the shearing action that takes place during gladhand connection. In the case of the common spring guard, the spring coils shift and do not prevent kinking and bending during installation and operation.
In particular, in the freight hauling industry, conventional air brake tube or hose fittings and tube or hose assemblies undergo stress during tractor-trailer connections and operation. The conventional non-swivel hose and tube fittings and assemblies prevent ease of connecting hose and tube assemblies to the tractor braking air supply lines and typically require the “cork-screwing” of fixed male fittings into fixed swivel fittings, or the disassembly and reassembly of the fittings during installation. During operation, fixed end fittings prevent rotation of hoses where some movement is desirable, such as during lift axle operation, putting further stress on the air brake hose and tube fittings and assemblies and leading to premature failure of the tractor-trailer air brake system. Prior art live swivel fittings do not provide sufficient support, free, (live) rotation and assembly integrity under stress or the long-term sealing qualities necessary in harsh environmental and operational conditions. Connection of conventional hose assemblies typically requires multiple wrenches to couple hose assemblies to fixed fittings or to join multiple hose assemblies. The use of crimped nuts in prior art live swivel fittings requires the use of materials such as steel rather than the more malleable brass to prevent over-torquing and leakage. This leads to corrosion issues and fitting seize-up.